An apparatus with an emission function in an application scenario configured with multiple antennas, such as a base station and a terminal in a multiple input multiple output (MIMO) communication system, often adopts a precoding technology to obtain higher transmission efficiency.
Taking downlink data transmission as an example, when performing data transmission, the base station and the terminal use a precoding matrix, and according to an obtaining manner of the precoding matrix, transmission may be further divided into an open-loop precoding transmission mode and a closed-loop precoding transmission mode. The open-loop precoding transmission mode is generally referred to as an open-loop mode for short, and in the open-loop mode, the base station selects the precoding matrix by itself and the terminal does not need to feed back the precoding matrix; and the closed-loop precoding transmission mode is generally referred to as a closed-loop mode for short, and in the closed-loop mode, the terminal needs to feed back the precoding matrix, and the base station selects the precoding matrix in combination with the feedback of the terminal.
In the closed-loop mode, a delay exists when the terminal feeds back the precoding matrix, so the movement speed of the terminal has large influence on performance of the closed-loop mode. Comparing the performance that can be reached in the open-loop mode and in the closed-loop mode, it is often considered that the higher the speed is, the better the performance that can be reached by the open-loop mode is, and on the contrary, the lower the speed is, the better the performance that can be reached by the closed-loop mode is. Therefore, in order to obtain better performance, a generally adopted solution is to determine whether to adopt the open-loop mode or the closed-loop mode according to the movement speed, which is specifically: when the movement speed is low, the closed-loop mode is adopted, and when the movement speed is medium or high, the open-loop mode is adopted.
In the conventional art, in the case of determining a transmission mode merely according to the movement speed of the terminal, the data transmission efficiency is low.